Rapid discrimination of graphene oxide in a silk fiber/GO composite by temperature-dependent two-dimensional...

In this study, a silk fiber/graphene oxide (GO) composite was directly obtained by feeding silkworm larvae with GO. Methods such as temperature-dependent Fourier transform infrared (FT-IR) spectroscopy, second-derivative analysis and two-dimensional (2D) correlation FT-IR spectroscopy were used to investigate the bonding interactions between GO and silk fibers in the silk fiber/GO composite. In addition, the silk fiber/GO composite was physically characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Temperature-dependent second-derivative FT-IR spectra of the reinforced silk fiber/GO composite showed a characteristic absorption band of GO at 1053 cm^-1 and 40 °C, confirming the incorporation of GO into the silk fiber matrix. 2D correlation analysis of the temperature-dependent FT-IR spectra indicated that the asynchronous correlation intensity of the silk fiber/GO composite decreased 1.7-fold compared with that of the silk fiber, and the number of correlation peaks was significantly reduced, which suggests that GO present in the silk fiber/GO composite is thermally reduced with increasing temperature, resulting in enhanced thermally stability. The results of TGA showed that the silk fiber/GO composite exhibits higher decomposition temperatures than the silk fiber, which is in good agreement with the temperature-dependent 2D correlation analysis.